Effect

Generation I

Explosion has a power of 170 in Generation I.

Explosion does damage, and causes the user to faint. Though its power is listed as 170, the target's Defense will be halved when damage from this attack is calculated, giving it an effective power of 340. The game rounds up to avoid infinite damage, so Explosion will then effectively have a power of 170 if used against a target with a Defense value of 1.

If Explosion breaks a target's Substitute, the user will not faint, though its image will be replaced by a blank image. Additionally, if the user of Explosion had a Substitute at the time of such a situation, uses Substitute later, or switches out, its regular image will once again become visible.

If the user of Explosion attacks first and faints itself, the target will not attack or be subjected to recurrent damage during that round.

In Stadium, if Explosion breaks a target's Substitute, the user will faint.

Generation II

Explosion's base power was changed to the current 250. The Defense-halving step still applies, giving it an effective power of 500.

Generations III and IV

Generation V

Explosion does not cause the user to faint, but instead cuts its HP in half, and affects all Pokémon, items, and walls within 2 tiles of the user, reducing HP by half on teammates, by 80 on hostile Pokémon, and destroying all walls, items, and special tiles. Explosion cannot be used in rain or on any floor with a Pokémon with the ability Damp.